The 94 and 95 are 5.0L. The 5.0 is not better but there are mor aftermarket parts for it. The 4.6 should get better gas mileage.
If you are going to supercharge it I would get the 4.6L because they respond to a supercharger very well.
As far as cost the 5.0 will be a little cheaper to modify.
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James Cox
nochevy@hotmail.com
1991 Mustang LX
12.565 @109.38mph 1.764 60ft